This work will address circulatory and epithelial influences affecting aqueous humor formation in the rabbit. In vivo studies will first define the effects of incident arterial pressure and flow upon simultaneously obtained measurements of regional ocular blood flow, the rate of aqueous humor formation, and IOP. Later experiments will examine changes in these relationships caused by common therapeutic and experimental drugs ( i.e. the catecholamines, acetazolamid, selected Beta-agonists, and vanadate). Studies will also be conducted to establish the extend of neurovascular influences on aqueous humor formation, by noting the effects of both sympathetic and parasympathetic (ganglionic blockers upon draug-induced chagnes to ciliary process blood flow, the aqueous formation rate, and IPO. A seperate and parallel study will ecamine the effects of topically applied epinephrine upon regional ocular blood flow in aphakic rabbit eyes. In vitro experiments will use the isolate rabbit ciliary epithelium to examine relationships between pressure-dependent changes of trans-epithelial fluid flow, and active solute transport. The unidirectional and net fluxes of sodium, chloride and bicarbonate will be characterized with respect to their dependence on trans-epithelial fluid movement, substrate concentration, the effects of metabolic poisoning, and specific transport inhibitors. Drugs known to affect the aqueous humor formation rate will then be examined to their influence on normally occurring transporat relationships. The data are expected to better define interactions between secretion and hydraulic conductivity in the isolated ciliary epiuthelium, and when combined with results fraom in vivo studies, enhance the present understanding of aqueous humor formation in the living rabbit eye.